Pump system with variable-pressure seal

A pump system, comprising:

• an impeller disposed within a pump casing having an inlet and an outlet;
• a motor;
• an impeller shaft coupled between the motor and the impeller and configured to impart rotation to the impeller upon activation of the motor;
• and
• a sealed bearing frame through which the impeller shaft extends, where the bearing frame is secured between the motor and impeller and includes an air vent that is closeable via operation of a float valve assembly upon flooding of the pump system.

A pump system, comprising:

• an impeller;
• a motor;
• and
• an impeller shaft coupled between the motor and the impeller and configured to impart rotation to the impeller upon activation of the motor, where the impeller shaft extends through a sealed bearing frame enclosure coupled between the impeller and the motor, and where first and second ends of the bearing frame enclosure are each sealed around the impeller shaft with a variable-pressure sealing system, including:
• a supply chamber in fluid communication with a cavity that surrounds, and is at least partially bounded by, the impeller shaft;
• and
• a pressure mechanism configured to pressurize lubrication matter contained within the supply chamber and cavity so as to inhibit liquid from passing along the impeller shaft through the cavity and into the bearing frame enclosure, where the pressure mechanism is configured to act upon the lubrication matter in the supply chamber to vary pressure of the lubrication matter during operation of the pump system based on atmospheric pressure surrounding the pump system.